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Reactions of Synthesis and Decay Properties of Superheavy Elements Yuri Oganessian Flerov Laboratory of Nuclear Reactions Joint Institute for Nuclear Research.

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Presentation on theme: "Reactions of Synthesis and Decay Properties of Superheavy Elements Yuri Oganessian Flerov Laboratory of Nuclear Reactions Joint Institute for Nuclear Research."— Presentation transcript:

1 Reactions of Synthesis and Decay Properties of Superheavy Elements Yuri Oganessian Flerov Laboratory of Nuclear Reactions Joint Institute for Nuclear Research Dubna, Moscow region, Russia HEAVIEST COMPOUND NUCLEI Third International Workshop on Compound-Nuclear Reactions and Related Topics (CNR*11) September 19-23, 2011, Prague, Czech Republic

2 92 U / T α = 4.5·10 9 a 82 Pb / stable Bi Th Macroscopic theory (charged liquid drop model) T SF = 1.0·10 16 a 102 No / T α ≈ 2 s. T SF ≈ a Z=106?

3 Fission Barriers …and Half - Lives R. Smolańczuk, Phys. Rev. C 56 (1997) 812 Predictions of the microscopic theory Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic

4 Neutron number P r o t o n n u m b e r New lands Microscopic theory LogT 1/2 s 1µs 1s1h a 1 Ma continent Island of Stability Peninsula Sea of Instability Отмель 106

5 Reaction of Synthesis

6 Reactions of synthesis Light ions Neutron capture Cold fusion target from “continent” Act.+ 48 Ca target from “peninsula” Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic

7 Compound nuclei excitation energy at the Coulomb barrier

8 SHE actinides deformed nuclei spherical nuclei Pb neutrons → protons → Reactions of Synthesis Neutron capture Fusion of massive Ions with Pb-target nuclei Cold fusion Since 1975 Light ion fusion with Act.- nuclei Hot fusion Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic

9 Cold fusion cross sections and fusion probability 1 event / year SHE E x =12-15 MeV Cold fusion Act.+ 48 Ca Z= E x =40-45 MeV Hot fusion

10 σ xn ~ (Γ n / Γ f ) x ; х – number of neutrons (Γ n / Γ f ) ~ exp ( B f – B n ) B f = B f LD + ΔE Shell 0 Cross sections Yu. Oganessian 2011

11 SHE Pb neutrons → Cold fusion Act.+ 48 Ca protons → Reactions of Synthesis Neutron capture Hot fusion Hot fusion Yu. Oganessian “Nuclei from Island of Stability of SHE” M-Lakes Conference Sept , 2011, Poland Targets from the n-rich isotopes of the elements heavier than 238 U Intense ion beam of the rare isotope - 48 Са

12 Decay chains Decay chains Pu, 248 Cm + 48 Ca Z= Talk at the Meeting of RAS, Nov., μs 0.7 ms s 0.5 min 2.5 s 0.06 s Yu. Oganessian 2011 Deformed shells Spherical shells

13 A/ZSetupLaboratoryPublications SHIPGSI DarmstadtEur. Phys. A32, 251 (2007) COLDPSI-FLNR (JINR)NATURE 447, 72 (2007) 286, BGSLRNL (Berkeley)P.R. Lett. 103, (2009) 288, , TASCA SHIP GSI – Mainz GSI Darmstadt P.R. Lett. 104, (2010) Eur. Phys. (to be published) Confirmations Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic

14 Odd-Z Superheavy Nuclei Synthesis of Isotopes with Z =113, 115 and 117 in 2010

15 Experiments on the synthesis of element 115 in the reaction 243 Am( 48 Ca, xn) 291−x 115 Yu. Ts. Oganessian et al., PRC 69, (R) (2004) RAPID COMMUNICATIONS spherical deformed Yu. Oganessian 2011

16 Reaction: → 249 Bk + 48 Ca → * → n T 1/2 =320d high neutron flux HFIR (ORNL) Yu. Oganessian 2010 high beam intensity of 48 Ca-projectiles U-400 (JINR) DGFRS High efficiency of separation 1 SH-atom/10 12 products Synthesis of Element 117

17 The Bk-249 was produced at ORNL (USA) by irradiation: of Cm and Am targets for approximately 250 days by thermal-neutron flux of 2.5  n/cm ² ·s in the HFIR (High Flux Isotope Reactor). Total dose : 4.3  n/cm ² Yu. Oganessian 2010 Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic

18 22.2 mg of Bk-249 Yu. Oganessian Ci Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic

19 Yu. Oganessian 2010 Beam dose: 2.4·10 19

20 Dubna Gas-Filled Recoil Separator Transmission for: EVR 35-40% target-like projectile-like Registration efficiency: for α-particles 87% for SF single fragment 100% two fragments ≈ 40% beam 48 Ca Experimental technique target

21 Number of random sequences imitating such decay chain is: 3· events of decay of isotope were observed in this experiment 1 events of decay of odd-odd isotope and Yu. Oganessian 2011

22 Yu. Oganessian T 1/2 = 320d 249 Bk + 48 Ca new isotopes 6 new superheavy elements Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic

23 Decay Properties

24 Yu. Oganessian 2011

25 P. Moller et al., Phys. Rev., C79, (2009) Yu. Oganessian 2011 deformed ▼ ▼ ▼ ▼ ▼ ▼ ▼ 108 cold fusion ▼ ▼ ▼ ▼ ▼ ▼ Z=117 Z=112 ▼ spherical ▼ ▼ ▼ Calculated fission barrier heights Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic

26 Cold fusion 100 Total evaporation residues cross sections (pb) Atomic number Cross sections 48 Ca-induced reactions SHE factor ~300 Yu. Oganessian 2011

27 ▼ ▼ ▼ ▼ Z=117 Z=112 ▼ ▼ ▼ Yu. Oganessian 2011 spherical deformed alpha decay spontaneous fission Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic

28 Trans-actinides Superheavy nuclei “critical” zones Spontaneous fission half-lives Actinides 48 Ca-induced reactions

29 Half-lives of nuclei with Z ≥ 110 Half-lives of nuclei with Z ≥ 110 Act Ca N=162 available for chemical studies Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic Yu. Oganessian 2011

30 With Z >40% larger than that of Bi, the heaviest stable element, we see an impressive extension in nuclear survival. Although SHN are at the limits of Coulomb stability, shell stabilization lowers ground-state energy, creates a fission barrier, and thereby enables SHN to exist. The fundamentals of the modern theory for mass limits of nuclear matter were given experimental verification.

31 neutrons → protons → Nuclear structure and decay properties of the SHN Nuclear Physics Chemical properties of the SHE Chemistry Search for new shells Nuclear theory Search for SHE in Nature Astrophysics Electronic structure of SHE-atoms Atomic Physics Yuri Oganessian “Heaviest Compound-Nuclei”(CNR*11), September 19-23, 2011, Prague, Czech Republic Z=117 N=175 T 1/2 =100 ms T 1/2 =1 ms Z=118 N=174

32 FLNR, JINR (Dubna) ORNL (Oak-Ridge, USA) LLNL (Livermore, USA) RIAR (Dimitrovgrad, Russia) Vanderbilt University (Nashville, USA) Collaboration Yu. Oganessian 2010 Thank you


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